Refrigeration



April 20, 1943. THOMAS 2,316,821

REfRIGERATION Filed Aug. 5, 1940 3 Sheets-Sheet 1 M MEL Aprifi 2%, i943A. R. THOMAS REERIGERAT ION 3 Sheets-Sheet 2 Filed Aug. 3, 1940 April20, 1943. A. R. THOMAS REFRIGERATION Filed Aug. 5, 1940 3 Sheets-Sheet 3wdL/l/yi moa zgmomw.

Patented Apr. 20, 1943 2,316,821 REFRIGERATION Albert R. Thomas,Evansville," Ind., assignor to Servel,.lnc., New York, N. Y., acorporation of Delaware Application August 3,3940, Serial No. 350,236

6 Claims. (Cl. 62-119) This invention relates to refrigeration, and moreparticularly to refrigeration apparatus of the absorption typeoperatedby heat.

In a low pressure refrigeration apparatus of this type containing only arefrigerant and an absorption liquid therefor as the two active fluidcomponents, a generator and condenser operate at one pressure and anevaporator and absorber operate at a lower pressure, and the pressuredifferential may be maintained by liquid columns. The system may containa water solution of lithium chloride, for example, with water as therefrigerant and lithium chloride solution as the absorption liquid. Inorder to circulate absorption liquid through and between generator andabsorber without a mechanical devicehaving moving parts, absorptionliquid is raised by gas or vapor-lift action in the generator, and theraised liquid flows to the absorber and returns from the absorber to thegenerator by gravity.

In low pressure refrigeration apparatus of the type just described, itis important that a substantially constant quantity of liquid iscirculated in the absorption liquid circuit, with variations in thequantity of circulating liquid being kept at a minimum. This isparticularly true when the refrigeration apparatus contains a saltsolution like a water solution of lithium chloride, for example, becausea high concentration of absorption solution must be used which is closeto the solidifying point. When the quantity of refrigerant out ofsolution and in parts of the system other than the absorption liquidcircuit becomes too great, the concentration of the absorption solutionbecomes sufiiciently high to cause such a quantity of salt toprecipitate that the passages in the absorption liquid circuit areclosed and blocked.

It is an object of the invention to provide an improvement inrefrigeration apparatus of the type described whereby a minimum amountof liquid is retained in the condenser, evaporator and absorber, so thatvariations in the quantity of absorption liquid circulating in theabsorption liquid circuit are at a minimum. This is accomplished byproviding an evaporator and an absorber in each of which a minimumquantity of liquid is retained, and locating the evaporator above theabsorber so that. after a fixed amount of refrigerant is out ofabsorption solution, the return of refrigerant to the solution is asrapid as the rate at which refrigerant is expelled from solution in thegenerator, whereby crystallizationof the solution is avoided.

It is another object of the invention to provide an improvedrefrigeration apparatus of the type described in which the evaporatorand absorber are located with respect to each other in such a mannerthat refrigerant vapor passes from the evaporator to the absorber in apath of flow in which the natural convection currents produced by thevapor are not .opposed by heavier noncondensible or inert gas which mayaccumulate within the refrigeration apparatus.

It is a further object of the invention to provide a supporting framestructure for refrigeration apparatus of the type described, and tomount the parts of the apparatus on the frame structure in such a mannerthat a compact arrangement of parts is effected with the evaporatormounted upon and directly supported by the absorber.

The invention, together with the above and other objects and advantagesthereof, will be more fully understood from the following descriptionand accompanying drawings forming part of this space, and of which:

Fig. 1 is a view more or less diagrammatically illustrating absorptionrefrigeration apparatus in which the present invention is embodied;

Fig. 2 is a front view, partly in section, illustrating absorptionrefrigeration apparatus, like that diagrammatically shown in Fig. 1,supported by a frame structure, the evaporator being disposed above andmounted on the absorber;

Fig. 3.15 a side view, partly in section, of the refrigeration apparatusand frame structure shown in Fig. 2, illustrating more clearly therelative position of the parts when the apparatus is viewed from thegenerator side thereof;

Fig. 4 is a side view, partly in section, of the refrigeration apparatusand frame structure shown in Fig. 2, illustrating more clearly therelative position of the parts when the apparatus is viewed from theabsorber side thereof; and

Fig. 5 is a plan view of the refrigeration apparatus and frame structureshown in Figs. 2 to 4 inclusive.

Referring to Fig. l, the present invention is embodied in a two pressureabsorption refrigeration system like that described in applicationSerial No. 239,762 of A. R. Thomas and P. P. Anderson, Jr., filedNovember 10, 1938, now Patent No. 2,282,503 granted May 12, 1942. Asystem of this type operates at low pressures and includes a generatoror expeller ID, a condenser ii, an evaporator i2 and an absorber I 4which are inter-connected in such a manner that the pressuredifferential in the System. is maintained by liquid columns.

The disclosurein the aforementioned Thomas and Anderson application maybe considered as being incorporated in this application, and, ifdesired, reference may be made thereto for a detailed description of therefrigeration system. In Fig. 1 the generator l0 includes an outer helll5 within which are disposed a plurality of vertical riser tubes ithaving the lower ends there- OfcQmmunicatingWith a space I! and theupper V condenser I.

through a U-tube 21' ends thereof extending into and above the bottom ofa vessel 18. The space |9 within shell l5 and about the tubes It forms asteam chambet to which steam is supplied through a conduit 20. The spaceI9 provides for full length heating of riser tubes l6, and avent 2| isprovided at the upper end of shell duit 22 is connected to the lower endof shell |5 above space H to provide 'a drain for condensate formed inspace IS.

The system operates at a partial vacuum and contains a water solution ofrefrigerant in absorption liquid, such as, for example, a water solutionof 40% lithium chloride by weight, with steam being supplied throughconduit 20 to space l9 at atmospheric pressure, heat is applied to tubesI8 whereby water vapor is expelled from solution. The absorption liquidis raised by gas or vapor-lift action with the expelled water vaporforming a central core within an upwardly rising annulus of the liquid.The expelled water vapor rises more rapidly than the liquid and thelatter follows along the inside walls of tubes l6.

The water vapor flows upwardly through the tubes or risers l9 intovessel l8 which is provided with an apertured baffle 23 and deflectors24 and 25 at each'side of the aperture in the baffle. The baffle 23 anddeflectors 24 and 25 serve 'as a vapor separator so that expelled watervapor isseparated from raisedabsorption liquid in vessel Hi and flowsthrough conduit 26 into The water vapor is liquefled in condenser H andthe water thus formed flows intoa flash chamber 28 and then intoevaporator |2.-

The evaporator l2 includes a plurality of horizontal banks of tubes29-disposed one above the other and to which are secured heat transferflns 30, to provide a relatively extensive heat transfer surface. Theend portions of thetubes 29 pass into spaced vertical headers 3|. Thewater flows from flash chamber 23 through a trap conduit 32 into aliquid distributing trough 33 from which the water flows into theuppermost horizontal bank of tubes 29. The water passes throughsuccessively lower banks of tubes through upright open end sections 34at the ends of tubes 29, any excess liquid being discharged from thelowermost bank of tubes 29.

The water supplied to tubes 29 vaporizes therein to produce arefrigeration or cooling effect with consequent absorption of heat fromthe surroundings, as from a stream of air flowin over the exteriorsurfaces of the tubes 29 and fins 30. The vapor formed in tubes 29passes out through the distributing trough 33 and open end sections 34into the headers 3| which are connected at their lower ends to absorberH. To prevent disturbances in evaporator |2 the flash chamber 23 isprovided to take care of any vapor fiashing'of liquid being fed to theevaporator through U-tube 21. vapor formed in the initial cooling of theliquid flowing from the condenser passes through a conduit 35.into oneof the headers 3| and mixes with'vapor formed in evaporator l2.

In absorber |4 refrigerant vapor is absorbed into concentratedabsorption liquid which enters through a conduit 36. The absorptionliquid flows from the upper end of conduit-36 into a liquid receptacleand distributor 31 in which liquid is distributed laterally of aplurality of vertically disposed pipe banks 38 which are arrangedalongside of each other.

15. A trap con- The liquid in The flashed erator ID by heating,

concentrated absorption conduit 41,

divided and passes into a plurality of smaller end compartments 39 fromwhich liquid flows through conduits 40 into a plurality of liquidholders and distributors 4|;extending lengthwise of and above the uppermost horizontal pipe sections of pipe banks 38. t 1

Absorption liquid siphons over the walls of the liquid holders 4| inginto and completely wetting the uppermost pipe sections. Liquid dripsfrom each horizontalpipesection onto the next lower pipe section wherebyall of first passage in liquid heat exchanger 43, conduit, vessel 45,and conduit 46 into the lower space ll of generator.

Water vapor is expelled out of solution in genand the solution is raisedby gas or vapor-lift action in riser tubes it, as explained above. Theabsorption liquid in vessel i8 is concentrated since water vapor hasbeen :expelled therefrom in generator Hi. This a second passage changer43, and conduit 36 into the upperpart of absorber |4'.

The vessel 45 is cylindrical in shape and dis- 1 posed about shell |5 ofgenerator I. The heating effectotthe steam. in space I9 is uid in vessel45. In this manner the absorption liquid flowing to generator l0 throughconduit 48 is preheated, as described more, fully in Thomas applicationSerial No. 347,631 filed July 26,1940. The upper part of vessel 45 isconnectedby a conduit 48 to. vessel l8 so that the pressure in vessel 45is equalized with the pressure in. the upper end of generator l0andcondenser The heat liberated with absorption of water vapor inabsorber I4 is transferred to a cooling medium, such as water, forexample, which flows upward through the vertically disposed pipe banks38. The cooling medium is supplied through a conduit to a horizontalmanifold 49 to which the lower .ends of the pipe banks 38 are connected,The upper ends of the pipe banks 38 are connected to a manifold 50 towhich is connected a conduit 5| zthrough which cooling mediumxleaves theabsorber H. The conduit 5| is connected to condenser so that the samecooling medium may be utilized to cool absorber l4 and condenser II,with the cooling medium flowing from condenser throughconduit 52 towaste.

The system operates at a low pressure with the generator l0 andcondenser operating at one pressure and the evaporator |2 and absorber|4 operating at a lower pressure, the pressure differential therebetweenbeing maintained by with drops of liquid fallthe pipe sections arewetted with'a film of liquid.

through-aconduit 42, a

liquid flows through a in liquid heat extransmitted through a portion ofshell I! "to absorption liqtween theinlet of absorber l4 and generatorHi. In operation, the liquid columns may form'in conduits 42, 4'! andthe down-leg of tube 21 to the levels 11:, y and z, for example. Theconduits are of such size that restriction to gas flow is effectedwithout appreciably restricting flow of liquid.

The liquid column formed in vessel 45 and conduit 46 provides the liquidreaction head for raising liquid in riser tubes I6 by vapor-lift action.The vessel 45 is of suflicient volume to hold the liquid differential inthe system and is of such cross-sectional area that the liquid leveltherein does not appreciably vary, so that a substantially constantreaction head is provided for lifting liquid in generator Hi. The vessel45 is located below absorber l4 such a distance that, for the greatestpressure differential occurring between absorber l4 and the upper partof generator in during operation of the system, the' of absorptionliquid still takes place from the' upper part of conduit 41 to the inletof absorber l4.

- In Figs. 2 to inclusive is shown refrigeration apparatus mounted on anopen frame structure, the apparatus being like that just described anddiagrammatically shown in Fig. 1, with similar parts referred to by thesame reference numerals. he base of the frame structure is rectangular Ir. ward from the corners of the rectangular base rmed by angle members58 and 54. As shown .11 Fig. 2, the angle members 56 at the rightandside of generator Iii extend upward for the xiii height of theapparatus, and the angle memyers 51 at the left-hand side of thegenerator exid upward approximately one-half the distance of'thevertical angle members 55.

The top part of the frame structure is also rectangular-shaped andincludes angle members $53 and 59, as shown most clearly in Fig. 5. Oneof the end angle members 58 overlies the upper ends of verticalanglemembers 56. Two vertical angle members 60 depend from the opposite.end

angle member 58 of the toppart of the frame structure. The lower ends ofvertical angle members 60 are substantially at the same height as theupper ends of vertical angle members 51 and are connected by horizontalangle members 6! which extend from the vertical angle members Bil to thevertical angle members 56. The lower ends of vertical angle members 60are also connected together by a cross angle member We.

All of the angle members just described are ,secured together, as bywelding or brazing, for example, to provide a rigid frame structure. Inorder to show the parts of the refrigeration, apparatus, and connectingconduits more clearly in Figs. 2 to 4 inclusive, the frame structure hasbeen shown in section in these figures. In Fig. 2 the front anglemembers 53, 59, B0 and BI are omitted and the angle members seen in thisfigure and referred to by these reference nushape and includes anglemembers 53 and 54. ur vertical angle members 56 and 51 extend and crossangle" member 60a are omittcd'and the vertical angle members seen'inthis figure are the angle members 56 at the right-hand side of generatori0 ii -Fig.2. b v

The absorber i4 of the refrigeration apparatus is mounted onand directlysupported by the horizontal angle members Iii.v As shown in Figs.

2 to 4 inclusive, two angle members 52 in spaced relation extendacross'the horizontal angle mernbers 6|. From the ends of angle members52 short angle members 63 extend upward and toward each other. Thehorizontal angle members 62. and inclined angle members 63 form cradlesupon which the shell of absorber I4 is mounted, the horizontal anglemembers having curved cut out portions to receive the rounded bottom'part of the absorber shell. The parts Just described are welded togetherto form a rigid.

I! include fiat inner wall members 64 and curved outer wall member 65having side wallportions which are secured to the edge portions of theflat inner wall members 64. The lower parts of wall members 84 and 65are cut away" so that the headers 3| can rest. upon and conform to thecontour of the rounded top portion of the absorber shell. The absorbershell is provided with openings corresponding to the shapes of theloweredges of headers 3 I, and the edges of these openings are securedby welding to the lower edges of the header wall, members 64 and 85.

Since the absorber i4 is supported directly on the horizontal anglemembers 6i and the. evaporator i2 is in turn mounted. directly on theabsorber, not. only is a strong and rigid support obtained for theseparts of the refrigeration apparatus, but a compact and novelarrangement of parts is effected with the evaporator. l2'and absorber l4occupying a minimum amount of space. It is desirable to mount theabsorber l4 and evaporator I! on the frame structure so that theevaporator tubes 28 and straight pipe sec tions of the absorber piping3B are substantially horizontal and level. In fabricating the evaporator, l2 and absorber H, the evaporator tubes 29 and straight pipesections of absorber piping 38 can be readily made parallel to eachother. mounting the evaporator I2 on the absorber I4,

. the evaporator tubes 29 andistraight pipe sections of the absorber canbe accurately leveled in a single operation when the absorber ism'ountedon the horizontal angle members 6|.

The generator I0 and parts associated therewith, which may be referredto as the generator assembly. are located within the vertical anglemembers 56 and 51 and secured to this part of the frame structure, as byspot welding, for example., The liquid heat exchanger 43 is also areconnected to the vertical angle members 56 I at the regions of vesselsl8 and 45, as shown in Fig. 2. "The bottom of vessel 18 is welded toangle member 66 and the bottom rounded end of vessel 45 is weldedtcfangle member The condenser ii is located above evaporator i2 andsupported in any suitable manner by the I angle members 58 and 59 at thetop of the frame member 58. As shown most clearly in Figs. 2 and 3, anangle bracket 69 is welded to the cross angle member 58 and to theanglebracket in turn is weldedthe' end of thecondens'er to which theconduit 52 is connected. I

parts is such that only a relatively small amount of refrigerant isretained in the condenser, evaporator and connecting conduits. Thecondenser H slopes toward the'outlet to' which U-tube 21 is connected,so that no liquid can accumulate therein except that utilized to wet thecondensing surfaces. The liquid condensate drains by gravity from thecondenser ll through U-tube 21 to the evaporator as fast as it is formedin the. con- In fabricating the refrigeration apparatus the generatorassemblyis arranged in the vertical frame section formed byverticalangle members 56 and 51 and secured to the frame by welding, asdescribed above,,and the evaporator-absorber I structure is secured inplace in the portion of the frame structure projecting from thevertically cxtending part. Either the generatorassembly or theevaporator-absorber structure can be first mounted on the framestructure, and the condenser assemblyis thereafter secured in position.

The conduits connecting the partsof the refrigeration apparatus in Figs.2 to 5 inclusive are the same as described above in connection with therefrigeration apparatus diagrammatically showninFigl, and furtherdescriptionthereof will not be made here. In order to show parts 'of therefrigeration apparatus more clearly in Figs. 2 and 3, the conduit llthrough which cooling medium flows from absorber H to'condenser "Ii isbroken away. Also, in Fig. 2 the trap'conduit 32 is shown as a verticaltube instead of an s shaped conduit as in Fig. l. The lower end of TheU-tube 21 through'which condensate formed with the down-leg locatedwithin the vertical angle members 56 and 51. The up-leg of u-tube 21includes a horizontal portion which extends across the top of absorberIL Y In Figs. 2 tot. inclusive it will be seen that all of theconnecting conduits except the up-leg of U-tube zl'are located at oneside of evaporator 42 and absorber I4 and occupy the space aboutgenerator In. The condenser li,-evaporator l2 andabsorber H are locatedone above the other and close together so that these parts will'occupy aminimum amount of space. Withthe evaporator l2 and absorber l4projecting from other (parts of the refrigeration apparatus located inthe upright section of the frame structure, the depth of therefrigeration apparatus is no greater than the narrow dimension of theevaporator and absorber, as shown in Figs. 3 to 5 inclusive. a Bylocating the evaporator 12 above the absorber it, any excess liquidrefrigerant passing from the lowermost bank'of tubes 29 in theevaporatorimmediately flows by gravity into the absorber, so that this liquid doesnot become trapped in a part of the apparatus and no special problemarises to effect return ofunevaporated refrigerant to the absorptionliquid circuit. Further, no. absorption solution canv get into theevaporator from the absorber by locating the former above the latter,whereby the relative position of the parts thereof which are free andclear, and internal screens are preferably employed to form a liquidfilm by capillary action, asdescribed in my application Serial No.350,235. filed August 3. 1940. Hence, the amount'of refrigerant that isretained in evaporator I2 is small and more or less a definite quantity.After thenxed amount of liquid is retained in condenser ll. evaporator12 and other parts during'operation of the system, the return ofrefrigerant to absorption solution is as rapid as the expulsion ofrefrigerant from solution in generator Hi. In this manner theconcentration of the absorptionsqlution is definitely controlled, sothat precipitation of salt and crystallizationof solution is avoided.

Suitable framed openings may be provided at each side of the evaporatortubes 29 to facilitate making duct connections thereto. The top of theabsorber shell and flat wall members 6 of the headers 3| serve as partof the duct passage through which air flows in thermal exchange relationwith the tubes 28 and fins 30 secured there- During operation of therefrigeration appa-' ratus non-condensible gas may form and collecttherein. These non-condensible gases may be referred to as inert gas andprovision may be made to remove the inert gas from the refrigerationapparatus, as bya vacuum pump, for example. By connecting the headers 3|of the evaporator to the extreme upper part of absorber shell, the mostdesirable flow of refrigerant vapor is obtained for trapping the inertgas. With water as a refrigerant, the wateryapor formed in theevaporator I2 is less dense than the inert gas. With segregating actionbeing effected between the inert gas andrefrigerant vapor, due to theconvection currents set up by-the vapor flowing from the evaporator IIto the absorber H, the inert gas tends to collect in the lower part ofthe absorber shell.

In any apparatus where there is condensation or absorption, the inertgas present will always be concentrated in the farthest point inthe lineof flow. In the arrangement of parts described and illustrated. thebottom part of the absorber she-ll at a region midway between theheaders 3| is the farthest point in the line-of flow of refrigerantvapor passing from the evaporator headers 3i. All of the inert gas isswept toward the middle or central region at the bottom of the absorbershell, the relative density of the refrigerant vapor and inert gas beingsuch that the convection currents do not tend to counteract theseparating action of the inert gas. However, if the refrigerant vaporentered the absorber at the extreme lower part thereof and tried tosweep the inert gas upward, the natural convection currents would beopposing the collection of heavier inert gas at the upper part of theabsorber. With the refrigerant vapor passing from the evaporator to theextreme upper part of absorber shell, the forces produced for sweepinginert gas to the farthest point in the line of vapor flow are in theproper direction.

For example, in a refrigeration system generally like that described andhaving an ice melting capacity of five tons, with the system operatingat'full load and the evaporator at a' temperature of about 50 F., theaverage velocity of the vapor escaping from the evaporator to theabsorber is about 130 feet per second. Under these conditions the vaporpressure in the evaporator is approximately 9.25 mm. mercury and thevapor pressure in the absorber is approximately 0.1 mm. mercury lower.With the vapor passing from the evaporator to the absorber at therelatively high velocity-just stated the forces produced by the escapingvapor are eifectively utilized to sweep inert gas to the bottom part ofthe absorber shell at a region midway between the headers 3|.

While a single embodiment of the invention has been shown and described,it will be apparent that modifications and changes may be made withoutdeparting from the spirit and scope of the invention, as pointed out inthe following claims.

What is claimed is: i

1. A multi-pressure absorption refrigeration apparatus having agenerator, a condenser, an evaporator and an absorber, and membersconnecting the aforementioned parts for circulation of refrigerant andabsorption liquid, the circulation of absorption liquid being effectedby vaporliquid lift action with the pressure differential between thegenerator and condenser on the one hand and the absorber and evaporatoron the other hand being maintained by columns of liquid, the absorberincluding piping over which liquid flows to keep the piping in a wettedcondition, and said evaporator including tubing inside of whichrefrigerant liquid flows and located relatively close to the absorberwith the refrigeration apparatus being so constructed and arranged thatthe absorber serves as a support for the evaporator.

2. In absorption refrigeration apparatus including a generator in whichrefrigerant vapor is expelled from absorption liquid, a condenser inwhich the expelled vapor is condensed, an evaporator in which thecondensate is evaporated, and an absorber including a shell into whichvapor from the evoporator flows downward in the absorber for absorptioninto liquid in the latter, the evaporator including tubing and headersinto which the tubing passes, the absorber shell having openings in thetop part thereof, and the lower parts of the headers being secured tothe shell at the openings.

3. In absorption refrigeration apparatus in cluclinga generator in whichrefrigerant vapor is expelled from absorption liquid, a condenser inwhich the expelled vapor is condensed, an evaporator in which thecondensate is evaporated, and an absorber into which vapor passes fromthe evaporator and connected to receive absorption liquid into which thevapor is absorbed, an open frame comprising metal members securedtogether to form a rigid frame structure, the refrigeration apparatusbeing mounted on the frame structure with the absorber being secureddirectly to certain of said metal members and the evaporator beinglocated above and mounted on the absorber.

4. In a multi-pressure absorption refrigeration apparatus including agenerator in which refrigerant vapor is expelled from absorption liquid,a condenser in which the expelled vapor is condensed, an evaporator inwhich the condensate is evaporated, and an absorber into which vaporpasses from the evaporator and connected to receive absorption liquidinto which the vapor is absorbed, the generator and condenser operatingat one pressure and the evaporator and absorber operating at a lowerpressure with the pressure differential therebetween maintained byliquid columns, the refrigeration apparatus being so constructed andarranged that the evaporator is located above the absorber, and a framestructure, the refrigeration apparatus being arranged on the framestructure in such a manner that the absorber is mounted directly on theframe structure and serves as a support for the evaporator.

5. Refrigeration apparatus including an open frame comprising metalmembers secured to form a rigid frame structure having an uprightsection and a section projecting from the upper part of the uprightsection, absorption refrigeration apparatus comprising a plurality ofinterconnected parts including a generator, a condenser, a liquid heatexchanger, an evaporator, andan absorber, the refrigeration apparatusbeing so constructed and arranged that the evaporator is located aboveand mounted on the absorber and the condenser overlies the evaporator,the refrigeration apparatus being mounted on the frame structure so thatthe absorber is secured to the metal members forming the projectingsection and other parts of the refrigeration apparatus including thegenerator and the liquid heat exchanger being located within the uprightsection of the frame structure.

6. In absorption refrigeration apparatus including a. generator, acondenser, an evaporator comprising tubing through which liquid flowsand having a plurality of straight sections alongside of each other, andan absorber including pipe sections arranged alongside of each other andover which absorption liquid flows, an open frame comprising metalmembers secured together to form a rigid structure, the refrigerationapparatus being so constructed and arranged that the evaporator islocated above and mounted on the absorber, the refrigeration apparatusbeing mounted on the frame structure with the absorber being secured tocertain of the metal members so that the pipe sections are substantiallyhorizontal, and the evaporator being mounted on the absorber so that thestraight sections of the tubing are also substantially horizontal.

. ALBERT R. THOMAS.

